It is known to heat parts of a vehicle which can be held, more particularly the steering wheel. For example, a steering wheel with an electric heater is known from DE 41 08 114 A1. There, a heat conductor made of copper wire is provided in the surface area of the steering wheel cover and is connected to a power supply device in the vehicle by a switch mechanism. In conjunction with a thermo-sensor, this serves to switch on the heater when required. From practice, it is known to operate the heater with a voltage of 12 volts and a current strength of 8 amps. As a result of this large current strength, it is standard practice to transfer the current from the battery through a contact unit with a slip ring/carbon brush to the steering wheel, because in the case of transfer by means of a strip conductor, the latter is no longer sufficiently flexible as a result of the minimum cross-section required, and because fewer conductors can be set in one contact unit and thus fewer consumers can be controlled.